Seam forming apparatus



April 9, 1968 w. H. BERRILL SEAM FORMING APPARATUS 4 Sheets-Sheet 1 Filed NOV. 4, 1966 Inven 2501's [ll/1 1 l am/7 Berri/l Raymond Hanson By zhez'rflfforney A ril 9, 1968 w. H. BERRILL SEAM FORMING APPARATUS 4 Sheets-Sheet 2 Filed Nov. 4, 1966 April 9, 1968 w. H. BERRILL 3,375,594

'SEAM FORMING APPARATUS Filed Nov. 4, 1966 4 Sheets-Sheet 5 April 9, 1968 w. H. BERRILL SEAM FORMING APPARATUS 4 Sheets-Sheet 4 Filed Nov.

Patented Apr. 9, 1968 3,376,594 SEAM FORMING APPARATUS William H. Berrill and Raymond Hanson, Leicester, EnglanrLassrgnors to United Shoe Machinery Corporation, F lemmgton, N1, a corporation of New Jersey filed Nov. 4, 1966, Ser. No. 592,072 Claims priority, application Great Britain, Nov. 19, 1965, 49,143/ 65 Claims. (Cl. 12-146) The present invention relates to apparatus adapted for use in forming a seam between two portions of sheet material, and more particularly to a device for use in forming a curved back seam between two quarters of a shoe upper.

In the manufacture of a shoe, and by the word shoe s meant outer footwear generally whether completed or in the process of manufacture, it is customary to form an upper which is later lasted and attached to a sole of a shoe. The upper is generally formed from pieces of sheet material, usually leather or plastic faced fabric, which are secured together to provide an upper of the desired shape. Generally in forming an upper, two portions of material termed quarters are joined together to provide a back seam which in the completed shoe extends down the back of the heel end portion of the shoe upper. It is usual for the back seam to be provided by stitching the two quarters together. From the foregoing, it is evident that both skill and time are required to provide a back seam which is strong and of pleasing appearance.

It is therefore, one of the various objects of the present invention to provide apparatus suitable for use in bonding quarters of an upper together to provide a back scam in the manufacture of a shoe.

Another more general object of the present invention is to facilitate the forming of a welded seam along adjacent edges of a thermoplastic material.

The apparatus, as hereinafter described, to illustrate the invention, by way of example, is one adapted for use in forming a curved back seam between the quarters of a shoe upper. The illustrative apparatus is of a type which can be readily mounted on a standard work bench and wherein the operating instrumentalities are pneumatically operated. It should further be understood that the two quarters herein described are of a plastic coated fabric material, each quarter comprising a curved edge portion as is customary in the art.

The illustrative apparatus comprises two work piece supports provided by first and second hinged bodies. With the apparatus at rest, the first and second hinged bodies are disposed in side-by-side relationship facing the operator. Pivotally mounted on each of the bodies is a clamp arm adapted to hold the work pieces in accurately located positions. In close proximity with the hinged bodies there is further located a form member comprising an upper work-engaging face provided by a first curved surface and a second curved surface which curved surfaces meet at a curved ridge portion of the form member. The apparatus also comprises means adapted to swing the hinged bodies into second positions one on either side of the form member, the illustrative means comprising pneumatically operated piston and cylinder arrangements. Additionally, each of the first and second hinged bodies is severally associated with means for assisting accurate location of the work pieces thereon which comprises first and second gage members pivotally mounted in the apparatus for movement between work piece locating positions and positions remote from the hinged bodies.

The apparatus further is provided with a clamp assembly adapted to be moved between a first position remote from the form member and a second position overlying and in close proximity to the form member when the hinged bodies are in their second position.

In the apparatus shown, the means for causing a seam to be formed between the work pieces comprises a generator adapted to create a high frequency electric field between the clamp assembly and the form member.

In a typical cycle of operation of the illustrative apparatus an operator positions a first quarter of a shoe upper on an upper work-engaging surface of the first hinged body and a second quarter on an upper work-engaging surface of the second hinged body. The quarters are located against the gage members in their work locating position. When accurately positioned, the quarters are clamped in their accurate location by the clamp arms. Depression of a foot pedal operates pneumatic means which is adapted to first move the clamp arms to clamp the quarters, then to move the gage members to their positions remote from the hinged bodies, further to swing the hinged bodies from their side-by-side position to their second positions in which curved edge portions of the first and second quarters overlie the first and second curved surfaces of the form member, the edge portions of the quarters being brought together, and finally to move the clamp assembly to its second position in which it overlies the curved edge portions of the quarters and presses them against the form member.

The operator then presses a button which causes the generator to create a high frequency electric field the heat from which is of sufi'icient magnitude to cause the seam to be formed along the juxtaposed portions of the quarters.

After a suitable time lapse, the generator is automatically switched ofif, the clamp assembly is moved to its first position, and the clamp arms release the quarters. The operator then removes the seamed quarters from the apparatus and a reset button is pressed to cause the various operating instrumentalities to be reset for a succeeding cycle of operation.

The various objects of the invention are achieved therefore by providing the illustrative apparatus which is effective for use in forming a curved seam between two portions of sheet material and more particularly as illustrated, it is eifective for use in forming a curved back seam between two quarters of a shoe upper, the seam comprising a butt joint wherein the shoe upper is joined along curved edge portions of the quarters which produces a substantially finished shape conforming generally to the heel end portion of an upper of a completed shoe. The seam thus produced in the manner hereinbefore disclosed is both strong and of pleasing appearance.

The aforementioned and other of the various objects and several features of the present invention will become clear from the following description, to be read with reference to the accompanying drawings, it being understood that the illustrative apparatus has been selected for description by way of example only and not by way of limitation thereof. Reference will now be made to the accom panyin g drawings wherein:

FIG. 1 is a right-hand elevational view showing various features of the illustrative apparatus;

FIG. 2 is a sectional plan view taken along the line II-II in FIG. 1, showing details of a portion of the apparatus;

FIG. 3 is a fragmentary front elevational view of the structure shown in FIG. 1 with the various parts in their inoperative positions;

FIG. 4 is a perspective view showing a shoe upper which has been operated on by the illustrative apparatus;

FIG. 5 is a vertical section taken along the line VV in FIG. 1, and showing various details of the structure taken on an enlarged scale for clarity;

FIG. 6 is a front elevational view similar to that of FIG. 3 but showing a part'of the structure on an enlarged scale and with the clamp arm open; and

FIG, 7 is a diagrammatic representation of a pneumatic circuit as employed in the illustrative apparatus.

Referring now to the drawings, in particular FIGS. 1 through 3 there is shown an illustrative apparatus comprising a frame 10 having an upper plate 11 and a lower plate 12, which plates 11 and 12 are of uniform thickness and are parallel one with the other. The plates 11 and 12 are spaced apart by columns 13 and are secured in this relationship by means of nuts 14. Supported by the frame 10 are the operating instrumentalities of the illustrative apparatus, which comprise a form member 16 having a work-engaging surface formed by curved side surfaces 18 and 19 which meet at a curved ridge 21 (FIG. A pair of clamp mechanisms 22 and 23 (FIG. 3) are mounted for radial movement between first open positions remote from the form member 16, and second closed positions adjacent to, and one on either side of, the form member 16. A pair of gage members 24 and 26 (FIGS. 1 and 3) are mounted for movement between first positions remote from the clamp mechanisms 22 and 23 respectively and second positions adjacent to the clamp mechanisms 22 and 23 when the clamp mechanisms are in their first positions as shown in FIG. 3. A clamp assembly 27 is mounted for up and down movement between a first position remote from the form member 16 and a second position in close proximity with the form member when the clamp mechanisms 22 and 23 are in their second closed positions.

The plates 11 and 12 of the frame are generally rectangular in plan, the plate 12 comprising a forwardly extending portion 28 and two rearwardly extending ears 29 and 31,

The form member 16 as best shown in FIGS. 1 and 5 is fixedly mounted on an upper surface 32 of the portion 28 and provides an upstanding elongated form extending forwardly and rearwardly of the illustrative apparatus which comprises two vertical side surfaces 33 and 34 bridged by the upper curved work-engaging surface comprising the surfaces 18 and 19. Each of the two surfaces 18 and 19 is constituted by part of the surface of a cylinder which by way of example may be approximately 5" in diameter, the axes of the surfaces 18 and 19 being at a right angle one to the other and intersecting at a point vertically below the ridge 21. The form member 16 also comprises a forwardly extending lug 36 having a vertical bore 37 therein, the axis of which is in alinement with the axis of a bore 38 in the plate 12. As will be noted, a short shaft 39 is fixedly mounted in the bore 37 and in the bore 38.

The clamp mechanisms 22 and 23 are similar in construction and operation, and therefore only the mechanism 22 will be described in detail. Referring in particular to FIGS. 5 and 6, the clamp mechanism 22 comprises a work support body 41 having lugs 42 and 43 whereby the body is hingedly mounted on the vertical shaft 39. An upper work-engaging surface 44 of the body 41 is part cylindrical and when in a cycle of operation of the apparatus the body 41 is swung into its second position, the surface 44 comes into contiguous relationship with the surface 18. When in an open position, the body 41 is swung forwardly so that the surface 44 faces the operator. Likewise, the clamp mechanism 23 also comprises a similar work support body 46 hingedly mounted to swing between its second closed position in which an upper work-engaging surface 47 is contiguous with the surface 19 of the form 16, and its first open position on the left of the form wherein the surface 47 faces the operator,

The body 41 also comprises a lug 48 disposed at an end portion remote from the hinged portion, the lug 48 having a threaded bore 49. Referring now to FIG. 1, it will be noted that a short shaft 51 is secured in the bore 49 and depends therefrom, while a block 52 is freely mounted on the shaft 51 and is secured thereon by a stop collar 53.

4. Fixedly mounted on the block 52 is a piston rod 54, the piston 56 (FIG. 7) of which is slidably mounted in a cylinder 57 extending rearwardly, and pivotally mounted on a pin 58 depending from the under side of the ear 31.

In operation, the piston rod 54 is moved by the piston 56 in the cylinder 57 to cause the clamp mechanism 22 to move between its first open position and its second, closed position. Likewise, the clamp mechanism 23 is arranged t to be moved by a piston and cylinder arrangement comprising a piston rod 59, a piston 61 and a cylinder 62 pivotally mounted on a pin 63. By means of this arrangement the clamp mechanism 23 is moved between its first open position and its second, closed position.

Referring now to FIGS. 5 and 6, the body 41 further comprises a cylinder A (FIG. 7) in the form of a lateral bore 64 which extends from the hinged end portion of the body 41 and terminates in a bore 66 of reduced diameter at an end portion of the body, remote from the hinged portion.

Slidably mounted in the bore 64 is a piston 67 comprising a piston rod 68 which extends through the bore 66, the rod 68 having an abutment 69 at an end portion remote from the piston 67.

The abutment 69 is adapted to engage a lower end portion71 of a clamp arm 72, which clamp arm is movable between a first clamping position and a second open position..The clamp arm 72 is mounted to swing about a horizontal pivot provided by a pin 73 secured to an upwardly projecting lug 74 at the end of the body 41 remote from the shaft 39. A work-engaging portion 76 of the arm 72 is arranged to overlie the surface 44 of the body 41 and an undersur'face 77 of the portion 76 is shaped complementary to the surface 44 and has a thin layer of rubber 78 fixedly mounted on the surface 77. A spring 79 is mounted on the piston rod 68 and is interposed between the body 41 and the lower end portion 71.

The spring 79 is adapted to urge the arm 71 to swing into its first clamping position, so that when a quarter 81 is placed on the surface 44 of the body 41 and air is exhausted from the cylinder A the pressure exerted by the spring 79 on the lower end portion 71 is sufficient to pivot the arm 72 in an anticlockwise direction as viewed in FIG. 6 about the pin 73, to clamp the quarter 81.

As best shown in FIGS. 3, and 5 through 7, the clamp mechanism 23 similarly comprises a clamp arm 821 adapted to be moved between a first clamping position and a second open position, the clamp 82 being moved by a piston 83 (FIG. 7) mounted for sliding movement in a cylinder B provided by a lateral bore 84 in the body 46, and a spring 86. Like elements of the clamp mechanism 23 perform to operate on a quarter 85 in a manner similar to those elements described above, with reference to the clamp mechanism 22.

The gage members 24 and 26 are associated with the clamp mechanisms 22 and 23 respectively. Their mode of operation and construction is similar, and therefore details of the gage member 24 only will be described. The gage member 24 comprises an arm 87 (FIG. 1) which is pivotally mounted on a block 88 by a pin 89. The block 88 is fixedly mounted on an undersurface 91 of the upper plate 1 1, the arm 87 being adapted to swing forwardly or rearwardly.

Pivotally mounted to the arm 87 by a pin 92 is a bifurcated end portion 93 of a piston rod 94. The piston rod 94 extends rearwardly and is connected to a piston 96, (FIG. 7) which piston is slidably mounted in a cylinder C. The cylinder C is pivotally mounted on a pin 97 which is secured in a block 98 secured to and depending from the upper plate 11. Likewise, as best shown in FIGS. 3 and 7, the gage member 26 comprises an arm 99 which is pivotally mounted on a block (not shown) on the undersurface 91, the arm being adapted for movement by a piston rod 101. A piston 102 (FIG. 7) is.

slidably mounted in a cylinder D pivotally mounted on a block (not shown) depending from the undersurface 91.

The arm 87 of the gage member 24 has a gage block 103 fixedly mounted on a lower end portion 104 of the arm. The gage block 103 has a work-engaging surface 106 which surface is part cylindrical and has mounted thereon a pair of protruding elements in the form of pins 107 and 108. Likewise the arm 99 of the gage member 26 comprises a gage block 103a having a part cylindrical surface 106a and pins 107a and 108a protruding from the sylin-drical surface.

Referring now to FIGS. 1 and 5, the clamp assembly 27 further comprises a rubber clamp pad 109 having curved clamping surfaces 111 and 112 of curvature corresponding to the curved surfaces 18 and 19. The pad 109 is mounted on a block 113 which is in turn connected to an end portion 114 of a dovetail slide member 116 by a pair of insulated posts 117 and 118. The member 116 has an upper portion which forms a cam surface 119. The member 116 extends upwardly through a clearance hole 121 in the plate 11 and is held captive against lateral movement by a block 122. The block 122 is securely mounted on an upper surface 123 of the plate 11 and comprises a dovetail slot 124 in which the member 116 moves up and down. Pivotally connected to an upper end portion 126 of the slide member 116, by a pin 127, is one end portion of the block 129. An opposite end portion of the block 129 is pivotally connected by a pin 132 to an end portion of a lever 134, which extends rearwardly and is pivotally mounted at a central portion by a pin 137. The pin 137 is securely mounted in a bracket 138 carried by the plate 11. The lever 134 has a rearward end portion pivotally connected by a pin 141 to a block 142 to which is connected a piston rod 143. The piston rod 143 and its connecting piston 144 (FIG. 7) are mounted in a cylinder 146 to which is secured a lug 147 pivotally connected to a lug 148 by a pin 149, the lug 148 being fixedly mounted on the upper surface 32 of the plate 12. When the illustrative apparatus is in use, the piston 144 is moved by air under pressure to cause the clamp assembly 27 to be moved between its first position and its second position.

The block 27, which. as aforementioned, is electrically insulated from the slide member 116, is connected by means of a flexible copper strip 140 to a terminal 145. From the terminal 145 a lead passes through a metal sheath 150 supported by a bracket at its forward end from which it is separated by insulated spacers (not shown) to a high-frequency generator G. Thus the block 27 constitutes one electrode of the high-frequency circuit, the other being constituted by the form member 16 which is grounded to the frame 10 of the machine.

Referring to FIGS. 1 through 5, in a typical cycle of operation of the illustrative apparatus, with the clamp mechanism 22 in its first open position and the gage member 24 swung into its second position the workengaging surface 106 of the gage member is in contiguous relationship with the surface 44 of the body 41. A quarter 81 is then placed on the surfaces 44 and 106 with an edge portion against the pins 107, 108. A quarter 85 is also placed on the gage block surface 106a with an edge portion adjacent the pins 107a, 108a, the clamp mechanism 23 and the gage member 26 being positioned as described above with reference to gage member 27 and clamp mechanism 22.

The operator by depression of means such as a foot pedal 158, schematically depicted in FIG. 7, causes operation of pneumatic means to clamp the quarters 81 and 85, move the gage members 24 and 26 from their second to their first position, and move the clamp mechanisms 22 and 23 from their open to their closed positions in which the curved edge portions of the quarters 81 and 85 overlie the curved surfaces 18 and 19 of the form member 16. As positioned the quarters 81 and 85 abut against each other in line with, and overlying the curved ridge 21 of the form 16, and the clamp assembly 27 is caused to move from its first to its second position in sequence with the operation.

Depression of a second means operates pneumatic means providing a signal to the generator G which creates a high frequency electric field between the clamp assembly 27 and the form member 16, heat generated being of sufiicient magnitude to cause quarters 81 and 85 to be welded together along the edge portions, thereby forming the curved seam. After a preset time interval an electrical signal switches the generator G oif and provides a pneumatic signal to move the clamp assembly 27 to its first position and in addition causes the clamp mechanisms 22 and 23 to release the quarters 81 and 85.

Referring to FIG. 7. the operating instrumentalities of the apparatus are motivated by pneumatic means, the power being supplied by a normal factory air supply line. When the apparatus is in its inoperative position air is admitted to lines 151, 152, 153, 154, 156 and 157. Pressurizing these lines causes the clamp arms 72 and 82 to be held in their second positions, the clamp mechanisms 22 and 23 to be held in their first positions, the gage members 24 and 26 to be held in their second positions and the clamp assembly 27 to be held in its first position.

In the operation as hereinbefore described, depression of a foot pedal 158 switches a valve VP and allows air under pressure to pass through a line 159 to switch a valve VD thereby causing the lines 151 and 152, and the cylinders A and B to be exhausted. The springs 79 and 86 act on the clamp arms 72 and 82 of the clamp mechanisms 22 and 23 to clamp the quarters 81 and 85 against the curved surfaces 44 and 47. Switching of the valve VD also allows air under pressure to fiow through a line 161 to switch pilot valves PV1 and PV2 thereby exhausting a line 162 through the pilot valve PV1 and pressurizing a line 163 through the pilot valve PV2 by connecting it with the line 157. Pressurizing the line 163 switches a valve VB causing the line 153 and the cylinders C and D to be exhausted and a line 164 to be pressurized. The resultant pressurizing of the line 164 is effective to cause the gage members 24 and 26 to move to their first positions. As the gage member 26 moves between its first and second position pilot valve PV3 is switched causing a line 166 to be exhausted, and a second pilot valve PV4 is switched thereby pressurizing a line 167 by connecting it through PV4 to the line 157. Air under pressure through the line 167 switches a valve VA which exhausts lines 15A and one end of the cylinders 57 and 62 which admits air under pressure to a line 168 tothereby pressurize the opposite end of the cylinders 57 and 62 and to move the clamp mechanisms 22 and 23 to their second positions.

As the clamp mechanisms 22 and 23 are moved to their second positions (best shown in FIG. 5) in which the curved edge portions of the quarters 81 and 85 overlie the curved surfaces 18 and 19 of the form member 16 and abut against each other in line with an overlying the curved ridge 21 of the form member, a pilot valve PV6 is switched. Switching of the valve PV6 breaks a connection between a pair of lines 169 and 171, a pilot valve PV5 is switched and connects the line 157 with a line 172 through the pilot valve PVS to pressurize the line 172 and switch a valve VC, switching the valve VC exhausts the line 156, pressurizes a line 173 and one end of the cylinder 146-causing the clamp assembly 27 to move to its second position. The clamp assembly 27 is adapted to trip a pilot valve PV7 which causes a line 174 to be exhausted, a connection between the lines 174 and 171 to be broken, a pilot valve PV8 to be switched causing the line 157 to be exhausted, and air under pressure to be admitted to the line 171. Further movement of the clamp assembly 27 causes a cam member 176 to trip a pilot valve PV10 in a generator circuit.

Depression of a button 177 switches a valve VG, admitting air under pressure to a line 178 causing the valve V10 to be switched thereby completing a circuit through a line 179 and a pressure switch PS. to the generator G. As previously described, the generator G is adapted to create a high frequency electric field around the butted edges portions of the quarters 81 and 85. Heat thus generated by the high frequency electric field at the form member 16 is of sufficient magnitude to cause the quarters 81 and 85 to be welded together along the joint line I of their curved edge portions, to form the curved seam shown in FIG. 4. A time control incorporated in the generator circuitry ensures that the high frequency electric field terminates after a time sufiicient to allow the quarters 81 and 85 to be welded together. This is achieved by supplying a signal to energize a solenoid Si thereby switching the valve VS connecting the line 171 with line 181 through the valve VS.

Air under pressure in the line 181 passes through a valve Vii and switches the valve VC, to exhaust the line 173, pressurizing the line 156 and thereby causing the clamp assembly 57 to be moved to its first position. Movement of the clamp assembly 27 to its first position moves the cam member 240 thereby resetting valve V10, and thereby preventing accidental tripping of the RP. circuitry. The pilot valve PV7 is also switched, thereby connecting the lines 171 and 174, admitting air under pressure to the line 174 and causing valve VD to be switched. Switching of the valve VD admits air under pressure to the lines 151, 152 and one end of the cylinders A and B thereby raising the clamp arms 72 and 82 and releasing the quarters 81 and 85, and also switches the pilot valves PV1, and the line 218, 163 to the line 210, 157 through PV2.

The joined quarters 81 and 85 (FIG. 4) are then removed from the illustrative apparatus which is then set for the next cycle of operation. Depression of a button 182 switches a reset valve VR admitting air under pressure through the lines 171, 162, the valve VR and a line 183 to switch the valve VA. With the valve VA in the switched position the line 168 and one end of the cylinder 57 and 62 is exhausted, air is admitted under pressure to the line 154 and the opposite ends of the cylinder 57 and 62 causing movement of the clamp mechanisms 22 and 23 towards their first positions. During movement of the clamp mechanisms 22 and 23 the pilot valve PVS is switched breaking the connection between lines 157 and 172, the pilot valve PV6 is switched and connects the line 171 with the line 169 through PV6 which admits air under pressure to the line 169 causing valve VB to be switched. Switching of the valve VB exhausts the line 164 one of the cylinders C and D, admits air under pressure to the line 153 and an opposite end of the cylinder C and D, thereby moving the gage members 24 and 26 to their second positions. Initial movement of the gage members 24 and 26 is effective to cause the valve PV4 to be switched thereby breaking the connection between the lines 157 and 167 and final movement of the gage members switches the valve PV3 connecting the lines 171 and 166, admitting air under pressure to the line 166 to switch the valve PV8, thereby exhausting the line 171 and pressurizing the line 157 in readiness for the next operating cycle.

A safety circuit is provided and may be utilized as follows: After the clamp assembly 27 has been moved to its second position and if the operator is not satisfied with the positions of the quarters 81 and 85 by depressing a button 184 the cycle can be reversed enabling the quarters to be realined. Pressing the button 184 switches a valve VE admitting air under pressure through a line 186 to switch the valve VC and thus reverse the cycle as hereinbefore described.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for seaming together two pieces of material comprising: a pair of work piece supports disposed in side-by-side relationship in a first position, means movable to a position adjacent said work piece supports for assisting the accurate location of work pieces thereon, means disposed adjacent said work piece supports for holding the work pieces on said supports in their accurately located positions, means operatively connected I for moving said work piece with said work piece supports supports one relative to the other to a second position to bring portions of the work pieces held thereon together, and means for forming a seam along the juxtaposed portions of the work pieces.

2. The apparatus of claim 1 wherein each of said pair of work piece supports has a surface for receiving a work piece with a marginal portion extending beyond an edge thereof and said means for assisting the accurate location of work pieces thereon comprises a pair of gauge members each having a work engaging surface,

and each of said work engaging surfaces having an element protruding therefrom and located such that with said supports disposed in said first position and said gauge members each moved to a predetermined position adjacent thereto, a pair of work pieces each disposed on one of said support surfaces and contacting one of said elements is accurately located for being in juxtaposition when said supports are moved to said second position.

3. The apparatus of claim 1 wherein each of said work piece supports has a surface for receiving a work piece thereon and said means for holding a work piece, on of said support surfaces and contacting one of said ele pivotally mounted on said form member and having a clamping surface movable from a first position remote from said support surface to a position adjacent said support surface for clamping a work piece therebetween.

4. The apparatus of claim 3 which is particularly adapted for seaming together two quarters of a shoe upper and wherein said work piece support surfaces are portions of a cylinder and said clamp arm surface is contoured to conform therewith.

5. Apparatus for forming a welded seam along adjacent edge portions of two pieces of thermoplastic material comprising: a pair of work piece supports movable relative one to the other, each of said work piece sup-. ports having a surface for receiving a work piece with a marginal portion projecting beyond an edge thereof, pressing means disposed in close proximity to said work piece supports and comprising a pair of spaced presser members movable relative to one another, means operatively connected with said work piece supports for moving said support surfaces from a first position to a second position wherein the work piece marginal portions are in adjacent relationship with one another between said presser members, means for mounting at least one of said presser members relative to the other to clamp the work pieces therebetwcen, increase in temperature between said presser members with the projecting portions of the work pieces disposed therebetween.

6. The apparatus of claim 5 wherein said means for producing an increase in temperature comprises a high frequency generator interconnected between said spaced presser members.

7. The apparatus of claim 5 which further comprises means movable to a position adjacent said work piece supports for assisting the accurate location of work pieces disposed on said support surfaces.

8. The apparatus of claim 7 wherein said means for accurately positioning work pieces on said work piece support surfaces comprises a pair of gauge members each having a work engaging surface, and each of said work.

engaging surfaces having an element protruding therefrom and located such that with said supports disposed in said first position and said gauge members each moved to a predetermined position adjacent thereto, a pair of workpieces each disposed on one of said support surfaces and contacting one of said elements is accurately located for and means for producing an being in adjacent relationship when said supports are moved to said second position.

9. A method of forming a welded seam along adjacent edge portions of two pieces of thermoplastic material which comprises the steps of providing a form member and a pair of work piece supports each movable from a remote position to a predetermined position adjacent opposite sides of the form member, placing a piece of thermoplastic material on each of the Work piece supports with a marginal portion projecting beyond the supporting surfaces of the respective supports, accurately locating the projecting edges of the work pieces beyond the supporting surfaces of the respective supports such that the work piece edges will be in adjacent relationship when the supports are moved to said predetermined position adjacent opposite sides of the form member, clamping each work piece to its respective work piece support while in the remote position, moving the work piece supports to said predetermined position adjacent opposite sides of the form member, pressing the marginal portions of the work pieces against the form member, and heating the edge portions of the work pieces to produce a welded seam along the adjacent edges of the work piece.

10. The method of claim 9 which is further characterized by the step of providing a high frequency generator and wherein the step of heating the edge portions of the Work pieces is performed by energizing the high frequency generator to provide heat at the form member of suflicient magnitude to produce a welded seam along adjacent edges of the work pieces.

References Cited UNITED STATES PATENTS 1,814,518 7/1931 McGrail 3655 2,415,401 2/ 1947 Ashworth 112-62 2,487,918 11/ 1949 Ashworth 112-62. 2,666,935 1/ 1954 Gilbert et a1. 1264 20 PATRICK D. LAWSON, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,376,594 April 9, 1968 William H. Berrill et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 8, line 29, before "of" insert one same line 29, after "said" insert work piece same line 29, "support should read supports same line 29, "surfaces and contacting one of said ele-" should read comprises a clamp arm Signed and sealed this 13th day of January 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

9. A METHOD OF FORMING A WELDED SEAM ALONG ADJACENT EDGE PORTIONS OF TWO PIECES OF THERMOPLASTIC MATERIAL WHICH COMPRISES THE STEPS OF PROVIDING A FORM MEMBER AND A PAIR OF WORK PIECE SUPPORTS EACH MOVABLE FROM A REMOTE POSITION TO A PREDETERMINED POSITION ADJACENT OPPOSITE SIDES OF THE FORM MEMBER, PLACING A PIECE OF THERMOPLASTIC MATERIAL ON EACH OF THE WORK PIECE SUPPORTS WITH A MARGINAL PORTION PROJECTING BEYOND THE SUPPORTING SURFACES OF THE RESPECTIVE SUPPORTS, ACCURATELY LOCATING THE PROJECTING EDGES OF THE WORK PIECES BEYOND THE SUPPORTING SURFACES OF THE RESPECTIVE SUPPORTS SUCH THAT THE WORK PIECE EDGES WILL BE IN ADJACENT RELATIONSHIP WHEN THE SUPPORTS ARE MOVED TO SAID PREDETERMINED POSITION ADJACENT OPPOSITE SIDES OF THE FORM MEMBER, CLAMPING EACH WORK PIECE TO ITS RESPECTIVE WORK PIECE SUPPORT WHILE IN THE REMOTE POSITION, MOVING THE WORK PIECE SUPPORTS TO SAID PREDETERMINED POSITION ADJACENT OPPOSITE SIDES OF THE FORM MEMBER, PRESSING THE MARGINAL PORTIONS OF THE WORK PIECES AGAINST THE FORM MEMBER, AND HEATING THE EDGE PORTIONS OF THE WORK PIECES TO PRODUCE A WELDED SEAM ALONG THE ADJACENT EDGES OF THE WORK PIECE. 